1. Field
Power driven dental scalers are well known. Of particular interest herein is a dental scaler having a vibratable scaling work tool for removing calculus, stain or plaque from teeth, which dental scaler utilizes a stream of water to aid in scaling efficiency and in removal of accumulated debris.
2. State of the Art
Of the power driven dental scalers currently available, most common are scalers utilizing a flow of compressed air or a solid-state ultrasonic transducer to cause a scraping type work tool to vibrate.
Typical of the earlier air-driven dental scalers are those of U.S. Pat. No. 3,082,529 and U.S. Pat. No. 3,444,622 to Mills et al, which scalers utilize an air-driven ball contained in a chamber. Movement of the ball against the walls of the chamber imparts vibration to the chamber, which vibrations are then transmitted to the scraping tool. A more recent type of air-driven scaler, described in U.S. Pat. No. 3,526,962 to Fuerst, utilizes a rotatable mandrel which has an irregularly-shaped tip engaged with a reciprocable block in which the mandrel tip is received.
It is characteristically a problem of these air driven scalers that much of the vibrational energy generated by the vibrator motor is transferred to the handle portion of the dental scaler rather than to the scraper work tool. Moreover, the modes of vibration of these scalers may change as moving parts of the vibration generating mechanism wear with time.
In U.S. Pat. No. 3,703,037 to Robinson, there is described a dental scaler which utilizes a solid state ultrasonic transducer to provide constant modes of vibration for coupling with particular types of work tools. One disadvantage of the ultrasonic scaler, however, is the cost of the transducer and its fairly sophisticated ultrasonic generator.
A different air-driven dental scaler is disclosed in U.S. Pat. No. Re. 29,687 to Sertich. This dental scaler has very few moving parts as compared to the aforementioned mechanically complicated air-driven scalers and provides efficient transfer of vibrational energy to a scraping-type work tool with relatively little vibration being transferred to the handle portion of the instrument. Moreover, this type of scaler provides uniform modes of constant vibration which may be matched with the vibratory modes of various types of work tools without the need for complicated electronic components.
It has been found that a flow of water over a tooth surface can provide increased scaling efficiency and patient comfort by lubricating and cooling the tooth surface and by flushing scaled debris and blood from the surface and area being cleaned. A work tool having a fluid path therethrough is described in U.S. Pat. No. 3,368,280 to Friedman et al. The fluid path consists of a narrow bore in the shank of the work tool itself or a bore in the wall of the work tool connector designed to direct the fluid flow over the dog leg of the work tool to impinge on the tip. A disadvantage of the Friedman device is that it is extremely difficult to accurately machine a narrow bore in the shank of the work tool, particularly when it is made of very hard materials, or to machine within the wall of the tool connector itself. Additionally, the bore opens into a plenum in the connector itself, resulting in a discontinuous inner surface which can cause an increase in the collection of debris and make cleaning difficult.
A solid state type dental scaler utilizing a flow of water to improve cleaning efficiency is described in U.S. Pat. No. 4,038,571 to Hellenkamp. One disadvantage of the Hellenkamp device, in addition to that of relatively high cost, is the shock hazard associated with the use of both electrical power and water in a hand-held instrument.
U.S. Pat. No. 3,375,583 (Blank et al) is directed to an ultrasonic dental tool having a work tool with a threaded end for engagement with a work holder member and an axial bore, which is counter-bored to receive a work tool element and a tube for transfer of water therethrough to impinge in a spray form on the extreme terminal end of the work tool. The tube extends out of the work tool, bridging substantially the entire length of the work tool element, to direct water onto the extreme terminal end of the work tool element. One disadvantage of the work tool described by Blank et al is that the water tube does not extend continuously between the ends of the work tool. Consequently, sediment and mineral deposits can collect in the area of the junction of the bore and counter-bore, and proper cleaning of the work tool in that area is difficult. Furthermore, the water tube extents into the work area of the work tool element where it can interfere with the proper operation of the work tool element on the teeth of a patient.
U.S. Pat. No. 3,075,288 (Balamuth et al) describes a dental instrument having an internal feed of water to the work area. A work tool holder is provided with a longitudinal passage intersecting a radial passage at its inner end which is normally closed by a valve. Actuation of the valve permits water to flow through the radial passage, into the longitudinal passage, through a slot in the work tool and over the work tool surface. That construction is not entirely satisfactory since the discontinuous surfaces are difficult to clean and tend to collect sediment and deposits.
It would be desirable to have a non-electrical, air-driven dental scaler having means for delivering water to the scaler tip which does not interfere with the operation of the scaler tip in the work area. Of particular advantage would be a relatively low-cost air-driven dental scaler having the scaling efficiency advantages of the "Sertich-type" scaler together with the advantage of water flow at the scaler tip to enhance the cleaning action.
A particular problem which occurs frequently in the use of dental instruments utilizing water transport tubes with small bores (such as 0.020 inch or less) is clogging of the tube with sediment or minerals carried in the stream of water. Hence, it is of benefit for a scaler to have a water supply tube that is easily accessible and can be cleaned quickly in the event it becomes clogged.
There is need, therefore, for an air-driven dental scaler having fluid transport means incorporated in the work tip assembly for delivering water to a scaling tip which is less prone to clogging and which can be easily and completely cleaned in the event clogging occurs.